I didn't think Walmart had any $800 bikes
If you're interested in a $200 to $300 bike... then Walmart might be an option. Not necessarily a forever bike, but hopefully you can ride it a few blocks.
At least here in the USA, the next step might be the mid-level sporting goods stores like Dick's Sporting Goods. They'll have some decent bikes. Nothing spectacular, but they'll be ok. I was disappointed that their support was minimal. Basic chains and etc, but nothing more.
Next step up might be REI. They're probably comparable to many of the lower end LBS stores, and usually have an in-store maintenance shop. I wouldn't have any qualms about shopping there. They're updating their product lineup for 2017, and it may also bring some good 2016 sales.
Then your LBS shops. Not all are the same.
I'd worry first about what type of bike you wish to buy. A Cyclocross or Hybrid would be high on my list. Then use that to help guide your decision of where to shop. You may find some stores don't carry the inventory that you're interested in.
Don't forget the used market, especially for the hybrids and old MTBs. But the best deals come with bikes needing work.